package com.algorithm.binarysearchnorecursion;

/**
 * @author 王林
 * @version 1.0
 * @date 2021-09-11 周六
 * @time 18:37
 * @description
 */
public class BinarySearchNoRecur {
    public static void main(String[] args) {
        //测试
        int[] arr = {1,3, 8, 10, 11, 67, 100};
        int index = binarySearch(arr, 100);
        System.out.println("index=" + index);//
    }

    //二分查找的非递归实现
    /**
     *
     * @param arr 待查找的数组, arr是升序排序
     * @param target 需要查找的数
     * @return 返回对应下标，-1表示没有找到
     */
    public static int binarySearch(int[] arr, int target) {

        int left = 0;
        int right = arr.length - 1;
        while(left <= right) { //说明继续查找
            int mid = (left + right) / 2;
            if(arr[mid] == target) {
                return mid;
            } else if ( arr[mid] > target) {
                right = mid - 1;//需要向左边查找
            } else {
                left = mid + 1; //需要向右边查找
            }
        }
        return -1;
    }

}
